Microbiological and chemical identification of antimicrobial drugs in kidney and muscle samples of bovine cattle and pigs

Abstract

Microbiological and chemical identification of antimicrobial drug residues was attempted in 95 kidney and 76 muscle samples from 58 cattle, 36 pigs and one horse which had revealed kidneys positive to an inhibitor test. Information on pre-slaughter medication with one antimicrobial drug was available for 63% of the carcasses. Microbiological identification was performed by agar diffusion using 17 or 18 combinations of eight test bacteria, varying medium pH and three substances blocking the action of certain antimicrobials. Sample activity patterns compiled from inhibition zone diameters on test plates were compared with those obtained with standard antimicrobial solutions both visually and by locating the minimal sum of absolute pairwise differences over the tests. Chemical identification of residues was based on liquid chromatography. In kidney samples containing one microbiologically-identified antimicrobial the two methods gave fully consistent results with tetracyclines (15/15) and fluoroquinolenes (8/8). Preparation and storage of the kidney samples before chemical analyses appeared to influence the chemical identification of penicillin G. The results were consistent in 37 of the 41 samples stored without homogenization at -70 degrees C. The residue was identified by chemical means only in six and neither microbiologically nor chemically in four kidney samples with information on pre-slaughter medication. The same residue as in the kidney samples was identifiable microbiologically in 41% of the muscle samples of the same carcasses. The results show that the microbiological method is well suited for identification of antibiotic residues. They indicate further that an enhanced resolution with a reduced combination of plates is attainable.

Comparison of three microbial screening methods for antibiotics using routine monitoring samples

“…Within the European Union, the EU 4 plate method [4] for several decades served as a reference method, but with the actual establishment of MRLs, the sensitivity of this method appeared insufficient for the MRLs in muscle. Several more sensitive methods have been developed since then [5][6][7][8][9], ranging from 5 to as many as 18 individual test plates.…”

Nouws antibiotic test: Validation of a post-screening method for antibiotic residues in kidney

“…Fortifying extracted matrix fluid (Cantwell & O'Keeffe, 2006) may give more realistic results, but still tissue binding is not taken into account. Alternatively, incurred samples obtained from routine monitoring programs have been used to evaluate the performance of a method (Currie et al, 1998;Myllyniemi et al, 1999Myllyniemi et al, , 2000Myllyniemi et al, , 2001Okerman et al, 2004). Such an approach however, is very much limited by the availability of these samples (residue type as well as concentration).…”

“…The EU-four-plate method, for example, was primarily proposed for testing muscle meat, but can be used also for kidney and liver, ''under the condition that a relative high risk for interfering factors should be taken into account" (Bogaerts & Wolf, 1980). Myllyniemi describes several multi-plate systems, that all are evaluated using both meat and kidney (Myllyniemi, Rintala, Bäckman, & Niemi 1999;Myllyniemi et al, 2001;Myllyniemi, Rannikko, Lindfors, Niemi, & Bäckman, 2000).…”

“…Application of a membrane or filter in between the agar plate and the kidney sample reduces the effect (Nolan, Dooley, Nugent, & O'Keeffe, 2000). Alternatively a cut-off value for the inhibition zone can be defined (Myllyniemi et al, 1999).…”

Aplicación de métodos microbiológicos en la detección de residuos de antimicrobianos en la leche de oveja.

“…Como técnicas de post-cribado actualmente, pueden utilizarse técnicas microbiológicas (Myllyniemi et al, 1999), inmunológicas (Dixon-Holland, 1992), radiológicas ( Korsrud et al, 1992), de luminiscencia ( Kurittu et al, 1999) electroforesis ( Cutting et al, 1995) o cromatografía en capa fina con bioautografía (Salisbury et a l., 1989).…”